Self-centering means for aircraft casterable landing wheel mountings



Oct. 21, 1952 H. SHAWBROOK EIAL 2,614,777

SELF-CENTERING MEANS FOR AIRCRAFT CASTERABLE LANDING WHEEL MQUNTINGS Filed June22, 1951 3 Sheets-Sheet 1 1,2 30 l ib-.. T

;Q Inventors Henry Shaw bm0k Edward A #11112) I Attorneys Oct. 21, SHAWBROOK r SELFCENTERING MEANS FOR AIRCRAFT CASTERABLE LANDING WHEEL MOUNTINGS Filed June 22 1951 5 Sheets-Sheet 2 Inventors Henry Shaurbrqok 'dumrd F2 Hillzer y W, VQ

Attorn eys O 1952 H. SHAWBROOK ETAL ,777

SELF-CENTERING MEANS FOR AIRCRAFT CASTERABLE LANDING WHEEL MOUNTINGS Filed June 22, 1951 3 Sheets-Sheet 3 Inventors lltnry S'bawbmok A ttorneys Patented Oct. 21, 1 952 I I SELF-CENTERING MEANsFoR AIRCRAFT, f i I I I CASTERABLE LANDING WHEEL MOUNT- mes Henry Shawbrook and Edward F. Hillier, Cheltenj f l hefxpresent invention relates to aircraft 'oastorable landing wheel mountings; and more particularly to what are commonly cal1edselfcentering means for resiliently returning the caster shaft of the mounting to a predetermined 'angularsetting at which the landing wheel is in a fore-and-aft alignment and from which it can such resilience.

. be fo'rciblyfswung in either direction against 1 a An object of the invention is to provide improved self-centering means operable throughout a predetermined angul'ar range at either side of the, centre position and permitting castoring throughout the remainder of the turning range.

M The invention consists in an aircraft castorable landing' wheel mounting, comprising a caster shaft carrying the wheel, fixed journal means able with said crank means throughout a predetermined angular turning of the same to either side of a centralposition at which the wheel is from said crank means throughout the remainder ,of its turning range, centering spring means ref acting oppositely upon the reciprocable means to returnthe same to an initial position corresponding to the centre position of the crank means jandvhence to. the fore-a nd-aft position of the wheel, and further spring means to permit yielding, in a direction radially of the crank means,

of one of the normally interengaged heads of the ham, England, assignorsqto Dowty Equipment 1. Limited, Cheltenham, England I a Appumm June 2 51 5 F??? N 232,908 I V '10- i (01." 244mm I Figure 1 is a sectional side elevation of one ex-v ample of aircraft castorable nose-wheel mounting having self-centering means in accordance with the invention; i I I H Figure 2 is an enlarged cross-sectionalview 'throu gh'the self-centeringmeans taken on: the

line Ill-11 of'Figure l; and r 1 i Figure 3 is a view similar to Figure 2 illustrating a modification. 1 I i The mounting shown in Figure 1 comprises a fixed outer casing I I adapted to be secured to the aircraft structure about a shaft extending thrbugh the bearing I2 in the lug "I3'so that the [in fore-andeaft alignment and disengageable I mounting can be retracted by retracting mecha- I nism (not shown) connected with the aper'tured 1 lug, I4. A castor shaftl5-isjournalled for 360" rotation within the casing I Iby journal bearings nates at its lower end in a rearwardly extending bracket I8 to which ispivoted at I!) a. lever 20 having a bearing 2I for the landing Wheel spindle.

Swinging of the lever 20 about its pivot I 9 is controlled by a shock absorber 22 pivoted at 23 to the le'verlfland at 24 to the castor shaft I5. The mounting includes self-centering mecha- H nisni for returning the castor shaft I5 intoa precrank and of the reciprocable means respectively,

fwhich had; been disengaged by relative rotation beyond the limits of the predetermined angular turning.

(The 'reciprocablemeansand the crank means preferably engage one another throughout the predetermined angular range by two heads such asa fork member on one of said means, e. g. the reciprocable means, and a resilient plunger memher on theother, of said meana'e. g. crank means,

said fork member having camsurfaces engageable by the plunger member during either direcltio'nfof return movement of the latter to its central position after disengagement from the fork member whereby to contract the plunger member determined alignment in whichfthe landing wheel extendsin a fore-'and-aft plane. The self -centeringinechanism comprises a spring boxgindicated generallyat 25, mounted on the fixed casing lll.

the crank or driving means; indicatedgenerally a slot 30in the plunger?! to permit the plunger ,toimove axially to an outer position limited by the slot but to prevent the plunger from rotating I about its own axis.

The spring box 25 comprises a reciprocable forked member 3| which together with a partition member 32 is secured by bolts33 to a tube34. The tube 34 is slidably mounted at its ends in cylindrical guides 35 fixed in the outer casing 1 II of the mounting. 'The structure comprising the fdrkedmember or head 3|, the partition "32 and the tube 34, isspring loadedto 'assume the TQFFlC-E mounted within the tube 34 and within the corresponding cylindrical guide 35. Each spring 36 reacts at one end against the end wall 31 of the cylindrical guide and at the other end against an abutment member in the form of a cup washer 38 carried on a stem. 39 whichis fixed to the end wall :31. A head 40 on the stem 39 limits the movement of the cup washer 38 away from The length of the stem 39 is 5 I the end wall 31. g adjustable by the screw and nut mechanism 4!.

The fork member 3| has a cent'ral channel in which the nose of the plunger 21 is received when the castor shaft I5 is in an angular posi- .and fork member 3| is returning to its central position, the entrapment of air beween the sta- -tionaryshock absorbing buffer 44 and the moving partition 32 cushions the impact between the tion corresponding to fore-and-aft alignment of I the wheel. The nose of the plunger 21 will remain in engagement with the groove 42 of the. forks member 3| for a predetermined degree of turning of the castor shaft IE to either sideof the central position, and turning of the shaft beyond;-

this predetermined angle will cause the plunger 21 to leave the groove 42 so that the wheel and the castor shaft are freed from the spring. box

. 25. The fork-member 3! has at each side of the groove 42 a cam surface 43 which is engaged by -the head of the plunger 21 during return movement of the latter in either direction to its central position after having become disengaged from the fork member. The appropriate cam surface 43 will engage the rounded sideof the head of the plunger 2'! and cause the plunger to contract against .the influence of its springs 29' to permit theplunger 21 to re-enter the groove .42 of .the fork member; thus the two heads reengage after their disengagement. The springs 36..of the self-centering spring boxwill'not 'pre- 7 vent castoring of the mounting but as soon as the aircraft becomes airborne-[and the landing .wheel is freed from the aircrafts weight, the springs 36 will act to return and hold the fork member or head 3| in its central position and thus. to return and hold the castor shaft and landing wheel in fore-and-aftalignment. During castoring of the landing wheel while the plunger 21 engages thegroove 42.0f the fork memben'th'e plunger 2! will cause the fork member to move .in. one direction and so to slide the tube 34and the partition v32 correspondingly; one of the springs 36 will then be compressed while its cup washer 3 8 slides along the stem 39 while the other spring 36 is unable to extend owing to engagement of its cup washer with the under surface of the head 40 of its stem 39.

' The self-centering mechanism above described thus operates upon the castor shaft throughout a predetermined degree of turning of said shaft in either direction away from the central posiin a position which differs little from the foreand-aft alignment. Once the aircraft becomes airborne the self-centering means will position and hold the castor shaft in the desired angular setting. I f V H j I Q In the modification shown in Figure 3 the stems Iii 39cofthe spring box are slidablethroughtheend walls 31a of :the springibox and, thesprings 36 iireact 3 between thegiid. walls {#310, and abutmentflfi M partition and buffer.

We claim: v .1. An aircraft castorable landing wheel mounting,'comprising a castor shaft carrying the wheel, fixed journal means supporting and guiding said shaft forrotation continuously through a 360 range, crank means fixed to said shaft and directed laterally thereof for rotation conjointly -.therewith, means reciprocable transversely of the castor shaft axis and engageable with said crank means throughout a predetermined angular turning' of the same to either side of a central position at which. the wheel'is in fore-and-aft alignment and disengageable from said crank means throughout the, remainder of its turning range. and centering springfmeans reacting oppositely upon the reciprocable means to return the same to an initial position corresponding to the centre position of the crank means and .hence to the forerand-aft position of the wheel.

2. .The'castorable wheel mounting defined in claim 1, wherein the reciprocable means and the crank means engage one another throughout the predetermined angular range by a fork memher on one of said means and a resilient plunger member on the other of said means, said fork member having cam surfaces engageable by the plunger member during either direction of return movement of the latter to its central position after disengagement fromthe fork member whereby to-contract the plunger member to permit it to .re-enter the fork member.

3. The. castorable wheel mounting defined in claim 2, wherein the plunger member is on the crank means, and the fork member is on the reciprocable'means' I 4.",Th'e cast rable wheel mounting defined in claim '1',,fwherein the reciprocable means comprises a'tube, andv said tube is 'slidable in oppositely disposed fixed cylindrical guides and formswith the same enclosures for two centeringjsprings. v

,S The' castorable wheel mounting defined in claim 4, wherein each ofjthe two centering springs reacts at itsouter end upon an end wall of the correspondingcylindrical guide and at its inner end upon an abutment member mounted slida'bly on the guide for limited movement away from its end wall into centering engagement with .a partition across the tube of the reciprocable .means.

6. The castorab'le .wheel mounting defined in claim 5., wherein shock absorbing buffer means is provided betweenjeach abutment member and the adjacent end of the partition.

Q .7. The: castorable wheel mounting defined in claim 5 wherein each abutment member is slidable on a stem extending fixedly fromthe' end -wall of the corresponding guide.

10. An aircraft castorable landing wheel mounting including a casing, an upright wheelmounting shaft, journal means supporting and guiding said shaft in said casing for 360 rotation, a crank arm formed with a head at its outer end and directed laterally from and mounted on said shaft for rotation therewith to swing its head in a definite arcuate path, means mounted and guided on said casing for reciprocative movement transversely of the axis of said shaft, and including a head thereby movable in a path disposed on a chord of the path of the crank's head to either side of a neutral or centered position, the two heads being normally engaged so long as rotative movement of the crank arm's head does not exceed the opposite limits of such chord, but being disengageable by rotative movement of the crank arm and its head beyond either such limit, resilient centering means operatively connected to said reciprocable means and reacting from said casing to return the reciprocable means head to said centered position whenever the two heads are not engaged, and tending to return the crank arm's head whenever the two heads are engaged, to said centered position, and further resilient means acting upon one of said heads to urge it into and to hold it in operative engagement with the other head, but yieldable in a direction generally lengthwise of the crank arm for reengagement of the two heads upon return of the crank arm and its head to centered position following disengagement of the heads and return of the reciprocable means and its head to such centered position.

HENRY SHAWBROOK. EDWARD F. HILL'IER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Dowty Feb. 27, 1951 

